JP2017048261A - Ink composition for aqueous ball point pen and aqueous ball point pen using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink composition for aqueous ball point pen capable of providing smooth writing feeling by enhancing lubricity between a ball and a chip body, good in writing touch and excellent in temporal stability by suppressing metal salts or the like generated in a ball pen chip.SOLUTION: There is provided an ink composition for aqueous ball point pen containing water, a coloring agent, an amino acid derivative, phosphoric acid ester-based surfactant having HLB value of 6 to 13 and a neutralizer, having one carboxyl group in a structure of the amino acid derivative and a relationship of 0.5≤B/A≤10, where A is total content of the amino acid derivative and the phosphoric acid ester-based surfactant to the all mass of the ink composition and B is content of the neutralizer to the total mass of the ink composition.SELECTED DRAWING: None

Description

  The present invention relates to an ink composition for water-based ballpoint pens, and more particularly, relates to an ink composition for water-based ballpoint pens having good writing quality and excellent stability over time by suppressing precipitates in the ballpoint pen tip. is there.

   Conventionally, ballpoint pens equipped with a ballpoint pen tip using a tip body made of stainless steel are well known. In the case of a water-based ballpoint pen using a chip body made of such a stainless steel material, precipitates such as metal salts generated by reaction of manganese ions and chromium ions such as manganese and chromium contained in the stainless steel material in the ink composition In order to prevent this, it has been proposed that the ink composition contains a corrosion inhibitor such as a benzothiadiazole compound or a metal sequestering agent.

  As an aqueous ballpoint pen using such an aqueous ballpoint pen ink composition, an aqueous ballpoint pen ink composition using a benzothiadiazole compound is disclosed in Japanese Patent Application Laid-Open No. 8-41409 “Aqueous Ballpoint Ink Composition”. .

  By the way, in order to improve the writing quality in Japanese Patent Publication No. 6-6689 “Water-based ballpoint pen ink to be supplied directly to a pen body”, an aqueous ballpoint ink composition containing a phosphoric ester surfactant as a lubricant is disclosed. ing.

"JP-A-8-41409" "JP-A-6-57194" "JP 2008-238457 A" "JP 2008-273105 A"

  However, Patent Document 1 proposes a water-based ballpoint pen ink containing a benzothiadiazole compound, but has problems of poor lubricity, poor writing quality, and blurring.

  Further, as in Patent Document 2, when a phosphate ester surfactant is contained as a lubricant in order to improve writing quality, a phosphate ester surfactant and a metal such as manganese ion or chromium ion in the chip are included. Reaction with ions generates metal salts. Furthermore, phosphate ester surfactants improve writing quality, but phosphate ester surfactants with particularly low HLB values tend to be more oleophilic and poorly soluble. There was a tendency that the metal salt produced by the reaction of the activator with the metal ions in the chip could not be completely dissolved and precipitates were likely to be generated.

  Therefore, in order to solve the above-mentioned problem, in Patent Document 3, the writing quality is good with an aqueous ballpoint pen containing carboxymethylpolyethyleneimine and in Patent Document 4 with an aqueous ballpoint pen containing aminopolyphosphonic acid. A technique for producing a water-based ballpoint pen excellent in stability has been disclosed.

  The objective of this invention is providing the ink composition for water-based ball-point pens which were excellent in writing quality, and were excellent in stability with time by suppressing the deposit by the metal salt in a chip | tip main body.

In order to solve the above problems, the present invention
“1. An aqueous ballpoint ink composition comprising water, a colorant, an amino acid derivative, a phosphate ester surfactant having an HLB value of 6 to 13, and a neutralizing agent. The total content with respect to the total mass of the ink composition of the amino acid derivative and the phosphate ester-based surfactant having one carboxyl group is A, and the content of the neutralizing agent with respect to the total mass of the ink composition An ink composition for water-based ballpoint pens, wherein when B, 0.5 ≦ B / A ≦ 10 is satisfied.
2. Content of the said amino acid derivative with respect to the ink composition total mass is 0.1-3.0 mass%, The ink composition for water-based ball-point pens of Claim 1 characterized by the above-mentioned.
3. 3. The aqueous ballpoint pen ink composition according to item 1 or 2, wherein the amino group of the amino acid derivative has a tertiary amine structure.
4). 4. The ink composition for water-based ballpoint pens according to any one of items 1 to 3, wherein an alkyl group of the phosphate ester surfactant is a linear alcohol type.
5. When the content of the amino acid derivative with respect to the total mass of the ink composition is X mass%, and the content of the phosphate ester surfactant with respect to the total mass of the ink composition is Y mass%, 0.1 ≦ Y / X ≦ 8. The water-based ballpoint pen ink composition according to any one of the first to fourth items, wherein the ink composition has a relationship of 8.
6). 6. The water-based ballpoint pen ink composition according to any one of items 1-5, wherein the water-based ballpoint pen ink composition comprises benzotriazole.
7). The water-based ballpoint pen ink composition according to any one of claims 1 to 6, wherein the colorant is a phthalocyanine pigment.
8). The water-based ballpoint pen according to any one of items 1 to 7, wherein a ballpoint pen tip made of a stainless steel material holding a ball rotatably is attached to a tip portion of the ink storage cylinder, A water-based ballpoint pen containing an ink composition for use.
9. The water-based ballpoint pen according to item 8, wherein the ball material is a cemented carbide.
It is.

  The present invention improves the lubricity between the ball and the chip body, smoothes the rotation of the ball, improves the writing quality, and suppresses precipitates due to metal salts in the chip body, thereby improving the stability over time. It was possible to provide an ink composition for water-based ballpoint pens excellent in water resistance.

  A feature of the present invention is a water-based ballpoint pen in which the total content of the amino acid derivative having one carboxyl group and the phosphate ester surfactant having an HLB value of 6 to 13 and the content of the neutralizing agent are set to a specific ratio. Ink composition for use.

  Phosphate ester surfactants are used to improve lubricity between the ball and the chip body and to smooth the rotation of the ball, thereby improving writing quality and facilitating wear control of the ball seat. Among them, it is necessary to use a phosphate ester surfactant having an HLB value of 6 to 13. This is because when the HLB value is 13 or less, the lipophilicity is increased, the lubricity of the ball is improved, the writing quality is improved, and the lower the HLB value is, the more lipophilicity is increased. If the HLB value is less than 6, the lipophilicity is too strong and the stability over time is affected.

  However, by including a phosphate ester surfactant in the aqueous ballpoint pen ink composition, metal ions such as manganese ions and chromium ions eluted from the chip body react with the phosphate ester surfactant. Metal salts may be generated. In particular, when a phosphate ester type surfactant having an HLB value of 6 to 13 is used, a metal salt having a strong lipophilicity is formed, so that a precipitate of an insoluble metal salt is generated in the ink composition. There was a problem that.

  In order to solve these problems of improving writing quality and suppressing the generation of precipitates due to metal salts, in the present invention, it is important to include an amino acid derivative having one carboxyl group in the aqueous ball-point pen ink composition. It is.

  For the amino acid derivative having one carboxyl group used in the present invention, the amino group of the amino acid derivative preferably has an alcohol structure (R—OH). This is because when these alcohol structures are included, the hydrophilicity tends to be strong, and the dissolution stability of the amino acid derivative in the aqueous ink composition is easily improved. Furthermore, amino acid derivatives having an alcohol structure in these amino groups are located outside the complex when coordinated to metal ions eluted from the chip body. Therefore, the presence of a strong hydrophilic structure on the outside of the complex makes it easier to improve the dissolution stability of the complex as a whole in the water-based ink composition. It is easier to obtain the effect. Therefore, it is preferable that a hydrophilic structure exists in addition to the carboxyl group in the structure of the amino acid derivative, and the amino group of the amino acid derivative preferably has an alcohol structure.

  Furthermore, examples of the amino group of the amino acid derivative having one carboxyl group include those having a structure such as a primary amine, a secondary amine, and a tertiary amine, and preferably a tertiary amine structure. This is because when the amino group of the amino acid is a primary or secondary amine, the hydrophilicity tends to be inferior, so that the carboxyl group is used for dissolution stability in the water-based ink composition. This is because it is difficult to obtain a precipitation suppressing effect. For this reason, the amino group of the amino acid derivative is preferably a tertiary amine having an alcohol structure.

  In the present invention, it is necessary to use a neutralizing agent. Thereby, the hydrogen ion of the carboxyl group of an amino acid derivative can be dissociated and the effect of enveloping metal ions can be promoted. Furthermore, since the phosphoric acid ester-based surfactant and an amino acid derivative having one carboxyl group in the structure are included, the ink has a strong acidity and affects the stability of the ink components. Therefore, it is necessary to adjust the pH value by adding a neutralizing agent.

  Regarding the content of the neutralizing agent, the total content of the amino acid derivative and the phosphate ester surfactant with respect to the total mass of the ink composition is A mass%, and the content of the neutralizing agent with respect to the total mass of the ink composition In order to achieve the effect of suppressing the generation of metal salt precipitates in the chip body, it is necessary to satisfy the relationship of 0.5 ≦ B / A ≦ 10. Furthermore, when B / A <0.5, the neutralization of the amino acid derivative and the phosphate ester surfactant is insufficient, and the ink becomes strongly acidic, affecting the ink aging stability, This is because if the influence of corrosion of a metal ballpoint pen tip or ball is generated, or if B / A> 10, the ink becomes more alkaline and affects the stability over time of the ink. Considering the ink aging more, the relationship 1 ≦ B / A ≦ 5 is preferable, and the relationship 1.5 ≦ B / A ≦ 3 is most preferable.

  Moreover, about pH value, 7.0-10.0 are preferable. This is because if the pH value is less than 7 and in the acidic region, it will affect the stability of ink components such as colorants and surfactants, and will affect the corrosion of metal ballpoint pen tips and balls. This is because even if the pH value exceeds 10 and approaches the strong alkali side, the influence on the stability with respect to the ink component is similarly generated. Considering more, the pH value is more preferably 7.0 to 9.0.

  As a specific example of the amino acid derivative having one carboxyl group, dihydroxyethyl glycine and / or a salt thereof is preferable in view of suppression of generation of precipitates due to a metal salt and suppression of corrosion of a ballpoint pen tip or a ball. Specific examples include Kirest G50 and Kirest GA (Chillest Co., Ltd.).

  On the other hand, if the content of the amino acid derivative having one carboxyl group is less than 0.01% by mass with respect to the total amount of the ink composition, the effect of suppressing precipitation of metal salt may be weakened. If it exceeds 0% by mass, the ink aging becomes unstable, so the content is 0.1 to 3.0% by mass with respect to the total amount of the ink composition. Considering more, 0.1 to 1.0% by mass is preferable with respect to the total amount of the ink composition, and most preferably 0.1 to 0.5% by mass.

For phosphate ester surfactants having an HLB value of 6 to 13 used in the present invention, phosphate ester surfactants having an HLB value of 7 to 12 are considered in consideration of lubricity and stability over time. In view of more preferable, phosphate ester surfactants having an HLB value of 10 to 12 are preferable. Phosphate ester surfactants include polyoxyethylene alkyl ether or polyoxyethylene alkyl aryl ether phosphate monoester, polyoxyethylene alkyl ether or polyoxyethylene alkyl aryl ether phosphate diester, polyoxyethylene alkyl ether Or phosphoric acid triesters, alkyl phosphoric acid esters, alkyl ether phosphoric acid esters or derivatives thereof of polyoxyethylene alkylaryl ethers, and the alkyl group of the phosphoric acid ester type surfactant includes styrenated phenol type, nonylphenol type Type, octylphenol type, lauryl alcohol type, tridecyl alcohol type, octyl alcohol type and the like. Among these, since having a phenyl skeleton tends to affect lubricity due to steric hindrance, the alkyl ester group of the phosphate ester surfactant is a linear alcohol lauryl alcohol, tridecyl alcohol, octyl alcohol, It is preferable to use a long-chain alcohol system (alkyl group having 10 to 15 carbon atoms). In consideration of lubricity and ink aging stability, it is preferable to use a lauryl alcohol type or a tridecyl alcohol type. You may use these individually or in mixture of 2 or more types.
In addition, HLB can be calculated | required from HLB = 7 + 11.7log (Mw / Mo) and (Mw: molecular weight of a hydrophilic group, Mo: molecular weight of a lipophilic group) as a general formula.

  In addition, specific examples of the phosphate ester-based surfactant include the PRISURF series (from Daiichi Kogyo Seiyaku Co., Ltd., lauryl alcohol-based products such as PRISURF A208B: HLB value 6, PRISURF 210B: HLB). Value 9, plysurf 213B: HLB value 12, tridecyl alcohol type, plysurf 212C: HLB value 9, plysurf 215C: HLB value 11, octyl alcohol type, plysurf A208F: HLB value 8, long chain Examples of alcohols include Prisurf 208N (mixture of alkyl groups having 12 and 13 carbon atoms): HLB value 7. These phosphate ester surfactants are used alone or in combination of two or more. May be.

  If the content of the phosphoric ester surfactant is less than 0.1% by mass with respect to the total amount of the ink composition, the desired lubricity cannot be obtained, the writing quality is poor, and there is a risk that the writing will be blurred. If the amount exceeds 5.0% by mass, the ink aging may become unstable. Therefore, the amount is preferably 0.1 to 5.0% by mass based on the total amount of the ink composition. In order to obtain good ink aging, the content of the phosphate ester surfactant is most preferably 0.5 to 3.0% by mass with respect to the total amount of the ink composition.

  Further, when the content of the amino acid derivative with respect to the total mass of the ink composition is X mass%, and the content of the phosphate ester surfactant with respect to the total mass of the ink composition is Y mass%, 0.1 ≦ Y / It is preferable that X ≦ 10. This is because when Y / X <0.1, the effective concentration of the amino acid derivative becomes excessive, and it is easy to show a stronger surfactant effect than the phosphate ester surfactant, and as a result, the phosphate ester surfactant. It is difficult to obtain a lubrication effect due to. Further, when Y / X> 10, it is difficult to suppress the metal salt generated by reacting with the phosphate ester surfactant. Considering more, a relationship of 1 ≦ Y / X ≦ 5 is preferable, and a relationship of 1 ≦ Y / X ≦ 3 is most preferable.

  Specific examples of the neutralizing agent used in the present invention include monoethanolamine, diethanolamine, triethanolamine, dimethylethanolamine, N-methylethanolamine, N-methyldiethanolamine, alkanolamines such as diisopropanolamine, triethylamine, Examples thereof include organic amines such as diethylamine, dipropylamine and amylamine, and alkali metal salts such as sodium hydroxide, potassium hydroxide and lithium hydroxide. Among them, it is preferable to use an organic amine in view of neutralizing and stabilizing the amino acid derivative and the phosphate ester surfactant, and in consideration, it is preferable to use an alkanolamine, and a weaker basicity. Most preferably, triethanolamine is used. These neutralizing agents may be used alone or in combination of two or more.

  Further, the content of the neutralizing agent is less than 0.1% by mass with respect to the total amount of the ink composition, and the neutralization of the amino acid derivative and the phosphate ester surfactant may be insufficient. If it exceeds 5.0% by mass, the ink aging may become unstable. Therefore, 0.1 to 5.0% by mass is preferable with respect to the total amount of the ink composition. 0.0 mass% is more preferable.

  In the present invention, in consideration of the stability of the pH value, or when a metal material is used for the tip body or ball material of the ball-point pen tip, it contains benzotriazole in order to easily suppress metal corrosion. It is preferable. In particular, a cemented carbide ball mainly composed of tungsten carbide uses cobalt, nickel or the like as its binder, and is easily affected by metal corrosion. Therefore, it is preferable that it contains benzotriazole.

  The colorant used in the present invention is not particularly limited, such as dyes and pigments, and can be appropriately selected and used. As the dye, direct dyes, acid dyes, basic dyes, metal-containing dyes, various water-soluble salt-forming dyes, and the like can be used. Examples of pigments include inorganic, organic, and processed pigments. Specifically, carbon black, aniline black, ultramarine, yellow lead, titanium oxide, iron oxide, phthalocyanine, azo, quinacridone, quinophthalone, selenium , Triphenylmethane, perinone, perylene, glyoxazine, aluminum pigment, pearl pigment, fluorescent pigment, phosphorescent pigment, and complementary color pigment. Alternatively, a microcapsule pigment obtained by encapsulating or solidifying a colored body in which a pigment is dispersed in a medium as a colored resin particle body in a shell made of a resin wall film-forming substance by a known microencapsulation method may be used. good. Further, colored resin particles in which the pigment is covered with a transparent or translucent resin or the like, or colored resin particles or colorless resin particles colored with a pigment or a dye can also be used. These dyes and pigments may be used alone or in combination of two or more. The content is preferably 1% by mass to 20% by mass with respect to the total amount of the ink composition.

  Among the colorants, when a phthalocyanine pigment is used, the structure with high metal affinity contains a large amount of metal ion impurities, etc., and ink aging stability due to deposits of metal salts by the phosphate ester surfactants It is effective because the effect of the present invention is remarkably likely to occur, and when using a copper phthalocyanine pigment, it is more effective because it is more likely to affect the ink aging stability. is there.

  In the present invention, a resin or the like may be used as an ink viscosity modifier or a pigment dispersant, and water-soluble resins such as acrylic resins, alkyd resins, cellulose derivatives, polyvinyl pyrrolidone, and polyvinyl alcohol, xanthan gum, and cross-linked acrylics. Examples thereof include shear thinning agents such as acid polymers, succinoglycans, gar gums, and jute gums, and associative thickeners such as alkali swelling associative thickeners and nonionic associative thickeners. You may use these individually or in mixture of 2 or more types. These ink viscosity modifiers and pigment dispersants may be used alone or in combination of two or more.

  Moreover, if the addition amount of the resin is less than 0.1% by mass relative to the total amount of the ink composition, it is difficult to obtain a desired ink viscosity, and if it exceeds 30% by mass, the writing performance may be deteriorated. Therefore, 0.1% by mass to 30% by mass is preferable, and 0.1% by mass to 5% by mass is preferable in consideration of more.

  In addition, considering the improvement of lubricity, surfactants such as fatty acids and silicones, humectants such as urea and sorbit, rust preventives such as benzotriazole, 1,2 benzoisothiazolin-3-one, etc. Antibacterial agents can be added. Also, a fixing agent can be added as appropriate, and an acrylic resin, urethane resin, styrene-butadiene resin, polyester resin, vinyl acetate resin, or the like can be added as a resin emulsion. These can be used alone or in combination of two or more.

  In addition, in order to improve writing quality and suppression of ink leakage, inorganic particles such as organic resin particles and silica may be used. In particular, organic resin particles are preferably used. Organic resin particles include olefin resin particles such as polyethylene resin and polypropylene resin, melamine / formaldehyde resin, benzoguanamine / formaldehyde resin, benzoguanamine / melamine / formaldehyde resin, urea formaldehyde resin. And nitrogen-containing resin particles containing a nitrogen atom in a chemical structure such as nylon resin, acrylic resin particles, styrene resin particles, epoxy resin particles, urethane resin particles, and cellulose resin particles. Furthermore, among organic resin particles, it is preferable to use olefin resin particles and nitrogen-containing resin particles in consideration of writing quality, suppression of ink leakage, and ink aging stability.

  As for the shape of the organic resin particles, those having a spherical shape or an irregular shape can be used, but spherical resin particles are preferable in view of reducing the frictional resistance. The spherical resin particle here is not limited to a true spherical shape, and may be a substantially spherical resin particle, a substantially elliptic spherical resin particle, or the like.

  Ballpoint pen tip materials include metal materials such as stainless steel, white, brass (brass), aluminum bronze, and aluminum, and resin materials such as polycarbonate, polyacetal, and ABS. Considering the properties, it is preferable to use a tip body made of stainless steel.

  Further, the ball-point pen tip ball is not particularly limited, but a cemented carbide ball mainly composed of tungsten carbide uses cobalt, nickel, or the like as its binder. The use of the metal material for the chip body or ball is preferable because it has a high affinity with a phosphate ester surfactant and a smoother writing quality can be easily obtained. On the other hand, when a conventional sequestering agent or the like is used in combination, there is a problem that the metal material of these cemented carbide balls is likely to be eluted. Therefore, it is preferable to use non-metallic ceramic balls such as silicon carbide. Since these non-metallic ceramic balls have a weak affinity for the metal phosphate balls with respect to the phosphate ester surfactant, the writing quality tends to be poor. The amino acid derivative having one carboxyl group is less likely to corrode over time against metals such as cobalt and nickel as compared with conventional sequestering agents, and may cause ball rotation resistance due to corrosion. And good writing quality can be obtained, and it can be suitably used for cemented carbide balls.

Next, an Example is shown and this invention is demonstrated.
Example 1
Water 57.8 parts by mass Water-soluble organic solvent (glycerin) 11.0 parts by mass Neutralizing agent (triethanolamine) 3.0 parts by mass Phosphate-based surfactant (tridecyl alcohol type, HLB value 11) Amino acid derivative (dihydroxyethylglycine) having 1 part by weight of carboxyl group
0.3 parts by mass Rust preventive agent (benzotriazole) 0.5 parts by mass Pigment dispersion (copper phthalocyanine pigment) 26.0 parts by mass shear thinning agent (xanthan gum) 0.4 parts by mass

  In Example 1, first, water, a water-soluble organic solvent, a neutralizing agent, a phosphate ester-based surfactant, an amino acid derivative having one carboxyl group, a rust inhibitor, and a pigment dispersion were heated at 40 ° C. with a magnet hot stirrer. Stir to make the base ink.

Thereafter, while heating the base ink produced, a shear thinning agent was added and sufficiently mixed and stirred using a homogenizer stirrer until a uniform state was obtained. Then, it filtered using the filter paper and obtained the ink composition for water-based ball-point pens of Example 1.
The ink viscosity of Example 1 was measured using a Brookfield DV-II viscometer (CPE-42 rotor) at a shear rate of 1.92 sec ⁻¹ (rotation speed 0.5 rpm) in an environment of 20 ° C. When the ink viscosity was measured under the conditions, it was 2500 mPa · s.
Moreover, when the pH value of Example 1 was measured at 20 degreeC using IM-40S type | mold pH meter (made by Toa DKK Corporation), it was pH value = 8.5.

Examples 2-7
A water-based ballpoint pen ink composition was prepared in the same procedure as in Example 1 except that each component was changed to the formulation shown in the table.

Comparative Examples 1-10
A water-based ballpoint pen ink composition was prepared in the same procedure as in Example 1 except that each component was changed to the formulation shown in the table.

Test and evaluation At the tip of the ink containing cylinder, a ballpoint pen tip that rotatably holds a cemented carbide ball having a ball diameter of φ0.7 mm is mounted in the ball holding chamber of the tip body made of stainless steel material, and the ink A refill in which the water-based ink composition and the grease-like ink follower prepared in Examples 1 to 7 and Comparative Examples 1 to 10 were directly filled in the containing cylinder was used as a gel ink ballpoint pen (trade name: manufactured by Pilot Corporation). The water-based ballpoint pen of the present invention was manufactured by attaching to Juice), and the following tests and evaluations were performed. In addition, using the copy paper (PPC paper) as a writing taste / writing test and a writing test paper, it evaluated by the following items.

Time-lapse test of chip body: After leaving the ballpoint pen refill in an environment of 50 ° C. and 0% humidity for 3 months, the ink in the chip body was subjected to a microscopic observation and a writing test.
Good without deposits ... ◎
Slightly generated precipitates, but no problem in practical use
Precipitates are generated and have a practical impact ... △
Precipitate is present and causes scumming or poor writing ・ ・ ・ ×

Writing taste: The ball-point pen refill was left standing for 3 months in an environment of 50 ° C. and humidity 0%, and then evaluated by a hand-written sensory test.
Very smooth ・ ・ ・ ◎
What is smooth ・ ・ ・ ○
Somewhat inferior ・ ・ ・ △
Heavy and inferior ・ ・ ・ ×

Ball Corrosion Test: After leaving a ballpoint pen refill in an environment of 50 ° C. and 0% humidity for 3 months, the state of ball corrosion was observed by a microscope and a writing test.
No corrosion of balls ... ○
The ball is corroded and the handwriting has a blur.
There is corrosion of the ball, there is a lot of shading in the handwriting, and the practicality is poor ... ×

  In Examples 1 to 7, good performance was obtained for both writing quality, chip body aging test, and ball corrosion test.

  In Comparative Examples 1, 9, and 10, since no amino acid derivative was contained, precipitates were generated in the chip body, resulting in poor writing.

  In Comparative Examples 2 and 8, since the phosphate ester surfactant having an HLB value of 6 to 13 was not contained, the writing quality was slightly inferior.

  In Comparative Example 3, it was not in the range of 0.5 ≦ B / A ≦ 10, and the neutralization of the amino acid derivative and the phosphate ester surfactant was insufficient. Scratch was generated or precipitates were generated in the chip body. In addition, the ball rotation was poor and the writing quality was slightly inferior.

  In Comparative Example 4, since the amino acid derivative having 4 carboxyl groups was contained, the ball was severely corroded and the handwriting was severely damaged. In addition, the rotation of the ball was poor and the writing quality was slightly inferior.

  In Comparative Examples 5 to 7, since the amino acid derivative having 2 to 3 carboxyl groups was contained, the ball was corroded and the handwriting was blurred. In addition, the rotation of the ball was poor and the writing quality was slightly inferior.

  Although not shown, when a coil spring that presses a ball made of stainless steel is disposed in the ballpoint pen tip, a phosphate ester interface having an HLB value of 6 to 13 as in the case of the tip body. Since the metal salt may be generated by the reaction between the activator and the metal ion of the coil spring, the effect of the present invention is remarkable.

  Furthermore, in an ink composition containing a pigment having a large particle size such as a pigment, there is a possibility of deterioration in writing quality due to rotation inhibition between the ball and the chip body, and a ball having a ball diameter of 0.5 mm or less was used. Since the ball pen has a small contact area between the ball and the ball seat, and there is a possibility that the writing quality is deteriorated due to a high load applied to the unit area, the effect of the present invention is remarkable.

  The present invention relates to an ink composition for water-based ballpoint pens, and more specifically, for water-based ballpoint pens comprising water, a colorant, an amino acid derivative, a phosphate ester surfactant having an HLB value of 6 to 13, and a neutralizing agent. The ink composition has one carboxyl group in the structure of the amino acid derivative, and A represents the total content of the amino acid derivative and the phosphate surfactant based on the total mass of the ink composition. When the content of the neutralizing agent with respect to the total mass of the ink composition is B, the writing quality is improved by using an aqueous ballpoint ink composition characterized by a relationship of 0.5 ≦ B / A ≦ 10. An ink composition for water-based ballpoint pens that is good and that is excellent in stability over time can be provided by suppressing deposits due to metal salts in the chip body. Therefore, it can be widely used as a ballpoint pen, such as a cap type and a knock type.

Claims (9)

An aqueous ballpoint ink composition comprising water, a colorant, an amino acid derivative, a phosphate ester surfactant having an HLB value of 6 to 13, and a neutralizing agent, wherein a carboxyl group is present in the structure of the amino acid derivative. 1 group, and the total content of the amino acid derivative and the phosphate ester surfactant with respect to the total mass of the ink composition is A, and the content of the neutralizer with respect to the total mass of the ink composition is B. In this case, a water-based ballpoint pen ink composition having a relationship of 0.5 ≦ B / A ≦ 10. Content of the said amino acid derivative with respect to the ink composition total mass is 0.1-3.0 mass%, The ink composition for water-based ball-point pens of Claim 1 characterized by the above-mentioned. The aqueous ballpoint ink composition according to claim 1 or 2, wherein the amino group of the amino acid derivative has a tertiary amine structure. The water-based ballpoint pen ink composition according to any one of claims 1 to 3, wherein an alkyl group of the phosphate ester-based surfactant is a linear alcohol type. When the content of the amino acid derivative with respect to the total mass of the ink composition is X mass%, and the content of the phosphate ester surfactant with respect to the total mass of the ink composition is Y mass%, 0.1 ≦ Y / X ≦ The water-based ballpoint pen ink composition according to any one of claims 1 to 4, which has a relationship of 8. The water-based ballpoint pen ink composition according to any one of claims 1 to 5, wherein the water-based ballpoint pen ink composition comprises benzotriazole. The water-based ballpoint pen ink composition according to any one of claims 1 to 6, wherein the colorant is a phthalocyanine pigment. A water-based ballpoint pen ink according to any one of claims 1 to 7, wherein a ballpoint pen tip made of a stainless steel rope holding a ball rotatably is attached to a tip portion of the ink containing cylinder, and the ink containing cylinder is filled with the ink for a water based ballpoint pen. A water-based ballpoint pen comprising a composition. The water-based ballpoint pen according to claim 8, wherein the ball material is a cemented carbide.